## Technical Support Document

For

Determination of Attainment and Redesignation

of the

Mammoth Lakes PM10 Nonattainment Area :

Analys es Addressing 2012 Incomplete Data

Environmental Protection Agency

– Region 9
Air Quality Analysis Office

Jennifer Williams and Gwen Yoshimura

April 30, 2015M ammoth Lakes PM10 Data Analysis Addressing Incomplete Data for Redesignation Purposes

Within the Mammoth Lakes Planning area there are two PM 10 monitors which are both located at the Mammoth Lakes site (06

- 051

- 0001). One of the monitors is a Federal Reference Method ( FRM ) manual monitor (POC 5) run at a sampling frequency of once every three days . The other monitor is a Federal Equivalent Method ( FEM ) continuous monitor (POC 6) run at a daily sampling frequency. Below are the 2014 Design Values (DVs) and DV validity for each monitor:

06

- 051

- 0001 POC 5: 0.0 expected exceedances , Valid

06

- 051

- 0001 POC 6: 0.7 expected exceedances , Invalid

Each monitor produces its own dat a stream, and t he data from the two monitors produce separate design values . As such, the highest 2014 DV for the Mammoth Lakes Planning Area is 0.7 , as measured by the POC 6 monitor, but this is an
invalid DV due to completeness issues with the data

. The following analysis examines what this invalid D V may mean for
the attainment status of the area.

To demonstrate attainment of the PM 10 NAAQS, three years of data with 75% of the scheduled PM 10 samples per quarter collected is required per 40 CFR Part 50, Appendix K, section 2.3(b). The POC 6 monitor at the Mammoth Lakes site did not meet the 75% completeness requirement in quarter 3 (Q3) of 2012 , therefore its 2014 DV, which uses data from 2012, 2013, and 2014, is considered to be invalid

. For 2012 Q3, the POC 6 monitor’s data completeness is 61% with a total of 36 missing days from August to September . The majority of the missing data is shown in EPA’s Air Quality System ( AQS ) database as invalid due to “Shelter Temperature Outside Limits” (AQS null data qualifier code “AE”). Since the DV is invalid, further analysis is needed to determine whether the missing data could reasonably have an effect on
the DV , specifically, whether it could have changed the DV from attaining to v iolating

.

Two monitors operate at th is site . As previously described

, the POC 5 monitor runs every

- third day, while the POC 6 monitor is scheduled to collect data continuously. A correlation graph showing results of a statistical analysis comparing
the tw o monitors with one another is included below. Looking at data from both monitors from 2009 to 2014, t he R 2 value for the simple linear regression is 0.9773 (n=680) , indicating that the data from the two monitors are well

correlated. For purposes of this a nalysis, this indicates that the POC 5 data, for the days that it collected data, well represents what the POC 6 data would have recorded. During the time period POC 6 did not collect valid samples, POC 5
measured values between 9 and 17 μ g/m 3 , well below the level of the PM 10 NAAQS.

However, since the POC 5 monitor d oes not sample daily, it is possible that there could have been exceedances during
POC 5 non

- sample days which POC 6, operating every day, would have captured had it measured va lid samples on those days . In order to determine whether it is reasonable to assume that exceedances did not occur in the missing timeperiod on POC 5 non

- sample days, identification of the high PM 10 season is useful. The first through fifth highest PM 10

c oncentrations from 2009

- 2014 measured by POC 6 occurred in the months of July or August. Of these highest concentrations, only the July 28, 2013 and July 29, 2013 concentrations were exceedances of the 150 μ g/m 3 standard. The next highest concentration, 13 3 μg/m 3 , occurred on August 1, 2014 and was not an exceedance of the standard.
W hile winter months do exhibit consistently elevated concentrations at Mammoth Lakes, over the past six years the highest PM 10 values were measured during the summer months

. The time series graph below shows data from 2012

- 2014 from both POC 5 and POC 6, and indicates the missing data period circled in red in 2012 as well as the maximum
values measured in years 2013 and 2014.

F or data from 2009 through 2014, the only two exce edances measured at Mammoth Lakes are flagged as wildfire exceptional events in AQS. W hile a demonstration package was not submitted for the dates, the Aspen Wildfire ( http://calfire.blogspot.com/2013/07/ca

- snf

- aspen

- wildlandfire

- 50

- acres.html ) occurred in the Mammoth Lakes area during the exceedance days.

While the late summer season appears to represent the maximum PM 10 concentrations at the site, since the only t wo exceedances in the last 6 years were due to a wildfire exceptional event, it is reasonable to conclude that the missing data would not reasonably have an effect on the DV.